Articles you may be interested inLarge-diameter roll mold fabrication method using a small-diameter quartz roll mold and UV nanoimprint lithography J. Vac. Sci. Technol. B 29, 06FC08 (2011); 10.1116/1.3657524Fabrication of a seamless roll mold using inorganic electron beam resist with postexposure bake J. Vac. Sci. Technol. B 29, 06FC06 (2011); 10.1116/1.3656052Fabrication of nanodot array molds by using an inorganic electron-beam resist and a postexposure bake Time-dependent exposure dose of hydrogen silsesquioxane when used as a negative electron-beam resist Fabrication of identical sub-100 nm closely spaced parallel lines using electron beam lithography Nanoimprint lithography ͑NIL͒ is the preferred technique for next-generation nanometer-scale patterning because of its cost effectiveness and simplicity when compared to conventional technology. The replicated pattern depends on the mold pattern, hence efficient methods for fabricating the fine mold are critically required and have recently become intensive subjects of research. This study reports a new method for the fabrication of a fine mold: this method uses low-acceleration-voltage ͑4 kV͒ electron beam lithography with spin on glass ͑SOG͒, which is used as a positive-tone inorganic resist. Although our SOG process does not contain chemically amplified material, postexposure bake ͑PEB͒ was characteristically used in the authors' process. The PEB process caused the annealing effect for the SOG and also suppressed the proximity effect. Consequently, a line-and-space pattern nanoimprint mold with a sub-50 nm spacing was fabricated at 4 kV using their process, and ultraviolet NIL was successfully carried out using the fabricated mold.

A high-aspect-ratio structural mold has been fabricated using a simple process that comprises of electron beam lithography (EBL) and post exposure bake (PEB) of inorganic resist. Using developed inorganic resist for mold, pattern transfer to a photo-curable polymer was carried out by ultraviolet nanoimprint lithography (UV-NIL). The developed inorganic resist has enough hardness to be used for mold because this resist structure is almost equivalent to that of quartz. The aspect ratio of the fabricated mold with PEB was 2.59; this value is twice the size of aspect ratio of fabricated mold without PEB (1.16). Thus, PEB is very effective in fabricating high-aspect ratio pattern in inorganic resist. The size of the fabricated mold with PEB was 1004 nm developed depth and 388 nm line and 252 nm space. Using the mold, UV-NIL was carried out. The size of replicated pattern was 942 nm height and 278 nm line and 241 nm space. The replicated height and line width were slightly smaller than mold depth and line width because of volume shrinkage of photo-curable polymer by UV irradiation. The aspect ratio of the replicated pattern using the mold with PEB was 3.39; thus, high-aspect-ratio transfer was also possible. This process is useful for rapid fabrication of quarter wavelength plates.